1. Field of the Invention
The present invention relates to a superimpose-plate for indicating a focused point, for example, in a view finder of a single-lens reflex camera.
2. Description of the Related Art
Conventionally, there is known a single-lens reflex camera provided with a function, in which a plurality of distance-measurement points are set for an image to be photographed, and a point, which is in-focus and included in the distance-measurement points, is indicated and superimposed on a subject image-in a view finder, as disclosed in Japanese Unexamined Patent Publication No. 2002-268128. Namely, a focusing glass and a superimpose-plate are superposed on each other, and disposed under a hollow pentagonal mirror, and if the number of the distance-measurement-points is seven, seven small focusing marks are formed on the superimpose-plate. A light-projecting optical system is provided in a rear portion or an emergent opening of the hollow pentagonal mirror and above an ocular optical system. In a photographing operation, when any point of the distance-measurement points is in-focus, an illumination light beam is radiated from the light-projecting optical system onto the corresponding focusing mark, so that the photographer can recognize the in-focus point.
Each of the focusing marks formed on the superimpose-plate is formed by lots of micro-prisms, which are inclined relative-to a surface of the superimpose-plate at an inclination angle that depends upon the position of the focusing mark. Namely, an illumination light beam is obliquely radiated from a light source, of the light-projecting optical system provided at a side of the emergent opening of the hollow pentagonal mirror. The radiation angle of the illumination light beam differs depending upon the position of the focusing mark, and the micro-prisms are inclined at an angle such that the illumination-light beam is effectively received.
Thus, since the inclination angles of the micro-prisms are different from each other, the manufacturing process of the superimpose-plate is complicated, which in turn makes controlling the manufacturing process difficult, resulting in increased manufacturing cost.
Further, for indicating a focusing mark by using lots of micro-prisms, it is preferable that the micro-prisms are gathered as closely together as possible.